Pressure operated arming mechanism



I Feb.'6, 1968 c. J. SEWELL 3,367,265

PRESSURE OPERATED ARMING MECHANISM Filed Jan. 26, 1967 Clinton J. Se'weH INVENTOR ATTO EY BY a 367 265 PRESSURE OPERATIlD ixRMlNG MECHANISM Clinton J. Sewell, Rockville, Md., assignor to the United States of America as represented by the Secretary of the Navy Filed Jan. 26, 1967, Ser. No. 612,298 5 Claims. (Cl. 10281) ABSTRACT OF THE DISCLOSURE The arming device includes a pivoted L-shaped shutter having an explosive charge normally spring urged to a position where the charge is out of alignment with a firing pin. The base of the shutter is provided with a flat surface upon which normally presses a crosspin mounted in a pressure responsive shaft and an arcuate surface over which the crosspin is located in response to a first pressure signal. A second pressure responsive shaft acts on the shaft in a manner that when a second pressure signal is applied it rotates the shutter to a position where the charge and firing pin are aligned. The shutter base is provided with a protuberance intermediate of its flat and arcuate surfaces which limits shutter movement only upon application of aparticular sequence of pressure signals.

Background of the invention The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to arming devices and more particularly to a fluid pressure operated arming device for an ordnance fuze.

There are many stringent requirements for arming devices when used in ordnance applications. They include compactness, ruggedness and high reliability after long storage life. When applied to fuzes, arming devices have safety features incorporated therein to restrain the firing pin and interrupt the explosive train so that premature ignition due to shock or vibration forces or other causes will not occur. Many of the presently available arming devices use an environmental power source, such as air pressure or underwater pressure, for the operating pressure to eliminate electric energy storage problems.

One of the drawbacks to this type of arming device is the possibility of premature firing by accidental application of high pressure or shock and vibration forces occasioned by mishandling of the projectile or missile with which the arming device is associated. This and other drawbacks can be overcome by the use of a low pressure fluid operating system containing independent locking and driving means which must be independently operated in a predetermined sequence.

Summary of the invention An object of the instant invention is the provision of a fluid pressure operated arming device for use in an ordnance fuze.

Another object of the present invention is the provision of a fluid pressure operated arming device having independently operated locking and driving means.

A further object is to provide a fluid pressure responsive arming device immune to shock and vibration.

A still further object of the invention is to provide a fluid pressure operated arming device requiring a particular sequence of application of pressure signals.

Briefly in accordance with one aspect of the invention, the foregoing and other objects are attained by an arming device having a pivoted shutter with vertical and base portions normally resiliently biased to an initial position.

3,367,265 Patented Feb. 6, 1968 "ice The base portion has a flat surface which initially engages a pressure responsive slideable element to lock the shutter in the initial position and a recessed portion over which the element is moved in response to a pressure signal thereby unlocking the shutter. A second pressure responsive slideable element engages the shutter and in response to a pressure signal urges against the bias on the shutter to affect movement thereof to a moved position.

Brief description of drawing A more complete appreciation of the invention and many of its attendant advantages will be readily appreciated as the same becomes better understood by reference to the detailed description when considered in connection with the accompanying drawing wherein:

FIG. 1 is a schematic representation of the essential operating elements of the arming device in an unarmed condition; and

FIG. 2 is a view, partially in section, of the arming device in an armed condition.

Description of the preferred embodiment As shown in the drawing, the delay arming device of this invention includes a closed casing 1 1 formed of a sidewall 12 and end bodies 13 and 14. Cylindrical bores or chambers, 15 and 16, are formed in end bodies 13 and 14, respectively, chamber 15 being provided with a wall 17 having an aperture 18 centrally formed therein. Cover plates 19 and 21 are secured by conventional means over the outer openings of chambers 15 and 16 and are provided with pneumatic input connectors 22 and 23 which admit pressure signals into the chambers from a fluidics system, not shown nor part of this invention. Pressure responsive members 24, 25, such for example as pistons or low-pressure consumption rolling diaphra'gms, are positioned within chambers 15 and 16 and are provided with shaft members 26, 27 extending into a chamber 28 centrally formed in casing 11. Diaphragms 24 and 25 are formed of a resilient material, such as rubber, which deflects or rolls down when pressure is applied thereto. Shaft 26 is encircled by a spring 29 normally urging piston 24 toward cover plate 19. The lateral movement of shaft 26 is restrained to a particular magnitude by aperture 18.

An L-shaped shutter 31 is pivotally suspended within casing 11 by a pin 32 and bracket 33 secured to casing wall 12. The shutter is formed of a solid vertical leg 34 having a bore 30 and a solid base member 35 perpendicular thereto and having a bore 36 formed therethrough. An explosive charge 44 is positioned in bore 36. The shutter is normally urged counterclockwise by a torsion spring 3 7 acting against a pin 38 and the casing. Base member 35 has a pair of identical parallel spaced legs 39 upwardly projecting therefrom each of which has an end surface with a flat portion 41, concave or recessed arcuate shaped portion 42 and a protuberance 43 intermediate of these two portions. The end of shaft 27 is disposed within bore 30 and is provided with a crosspin 40 to act against the urging force of torsion spring 37, as will be explained more fully hereinafter.

Normally, torsion spring 37 urges shutter 31 counterclockwise until piston 25 abuts cover plate 21, or in the alternative base body 35 rests against end member 14, in which position the explosive charge 44 will be out of alignment with a firing pin 45 of the associated fuze thereby maintaining an unarmed or safe condition. In this position, by the action of spring 29 a crosspin 46 secured in shaft 26 presses on the flat surface portions 41 of legs '39 thereby preventing clockwise rotation of shutter 31 by any shock or vibration forces to an armed position where firing pin 45 is aligned with explosive charge 44.

In effect, the arming device is locked in a safe position.

Upon application of a pressure signal of a predetermined magnitude to diaphragm or piston 24 generated by a fluidics system employing environmental pres-sure, such for example as the stagnation pressure at the nose of a bomb, spring 29 is compressed and shaft 26 moves crosspin 46 out of engagement with flat surfaces 41 and above arcuate surfaces 42 thereby unlocking shutter 31 from its safe position. Under this circumstance, shutter 31 is free to rotate in a clockwise direction, as determined by the depth of arcuate surfaces 42 except for the biasing action of torsion spring 37. Upon the application of a second pressure signal of a predetermined magnitude to diaphragm, or piston, 25 by the fiuidics system,

shaft 27 drives against vertical leg 34 overco-ming'the bias of torsion spring 37 thereby rotating shutter 31 to an armed position where explosive charge'44 is aligned With firing pin 45. Thus, it will be apparent that shaft 26 operates to lock. the shutter in a safe position and shaft 27 operates to drive the shutter to an armed position. The shutter may be locked in the armed position by a detent 47 on engaging a recess (not shown) formed in the sidewall or by any other conventional latching device which in addition willassure alignment of the charge and firing pin.

It will be appreciated by those skilled in the art that the requirement of oppositely directed pressure signals to provide for shutter movement provides further protection against premature arming by accidental shock or vibration forces. It should also be noted that a further safety provision is provided by the small protuberance 43 formed on shutter arms 39 which guards against movement of the shutter 31 if a pressure signal from the fiuidics system is first applied to chamber 16.

Obviously, numerous modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specificallydescribed.

herein.

I claim: '1. An arming device comprising a pivoted shutter having a vertical and a baseportion,

said base portion having fiat and recessed surfaces,

formed thereon, resilient means normally biasing said shutter to an initial position, first pressure responsive means initially engaging said flat surface for locking said shutter in said initial position and movable into operative relationship with said recessed portion in response to a pressure signal thereby" freeing said shutter' for=movement,;a nd second pressure responsive means engaging said shutter;

for affecting movement thereof from said initial posi tion to a moved position in response to a pressure signal.

2. The arming device of claim 1 and including l V I means formed on said base portion of said shutter for precluding movement of said shutter unless a pressure signal is applied to said first pressure responsivemeans before said second pressure responsivemean.

3. The arming device of claim 2.wherein said meansv for-med on said base portion comprises a protuberance intermediate of said fiat and recessed surfaces thereof.

4. The arming device of claim 3 wherein said recessed surface is arcuate shaped.

No references cited.

BENJAMIN A. BORCHELT, Primary Examiner. n G. H. GLANZMAN, Assistant Examiner. 

